Differences in viral decay and production following exposure to sunlight and darkness

Abstract

Abstract Although we have gained insight into the biological and biochemical effects of natural sunlight exposure on prokaryotes, little is known about sunlight exposure on natural virus communities. To fully understand the mechanics of microbial food webs, it is essential to understand the dynamics of viral infection of bacteria and its role in bacteria-mediated processes when sunlight is present or not. An investigation of the effects of sunlight and darkness treatments on viral communities, viral production and decay rates in Kenting coastal waters was conducted. A linear increase in viral abundance was observed in the darkness treatment as expected in the viral production experiment, the average rate of net viral production in the darkness treatment was 0.018 × 106 viruses mL–1 h− 1. However, within the first 12 hours after exposure to sunlight, viral abundance increased non-significantly in the viral production experiments. Further, averaged value for viral decay in the sunlight treatment was nearly 0.038×106 virus mL− 1h− 1. The rate of viral decay almost equaled the rate of gross viral production under natural sunlight treatment, resulting in gross viral production of nearly 0.038×106 virus mL− 1h− 1. Furthermore, we estimated that the gross viral production was nearly 0.018×106 virus mL− 1h− 1 in the darkness treatment. As a result, sunlight damages a large portion of the natural viral community, affecting the role viruses play in food webs. We understanding how viruses change under significant sunlight pressures suggests considering the temporal variations of viral production in relation to diel variations.